Move cpu0_stack out of Xen text section and into BSS. This

avoids getting loads of bogus cpu0_stack lines in call
backtraces from non-debug builds.

Doing this requires greater alignment of the BSS section,
which reveals a bug in ld where the alignment padding is
not added to the program segment's memsz field. We get around
this by finding the address of the last symbol in the image,
and increasing our load image's memsz to include that symbol.

Also some cleanups to the linker scripts.

Signed-off-by: Keir Fraser <keir@xensource.com>

diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
index ecd0b64e68480f1ef1f3249025f7f86f3de442ce..952327cc169225b8b6be656543dce99da594ee9f 100644 (file)
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -37,7 +37,8 @@ endif
 default: $(TARGET)
 
 $(TARGET): $(TARGET)-syms boot/mkelf32
-       ./boot/mkelf32 $(TARGET)-syms $(TARGET) 0x100000
+       ./boot/mkelf32 $(TARGET)-syms $(TARGET) 0x100000 \
+       `nm $(TARGET)-syms | sort | tail -n 1 | sed -e 's/^\([^ ]*\).*/0x\1/'`
 
 $(CURDIR)/arch.o: $(OBJS)
        $(LD) $(LDFLAGS) -r -o $@ $(OBJS)

diff --git a/xen/arch/x86/boot/mkelf32.c b/xen/arch/x86/boot/mkelf32.c
index 8fb665e0688587f77ef29e8ba0478a8f1a92e717..e93dfdcf96ba31a650de6c3082664c101bcfc0a1 100644 (file)
--- a/xen/arch/x86/boot/mkelf32.c
+++ b/xen/arch/x86/boot/mkelf32.c
@@ -222,6 +222,7 @@ static void do_read(int fd, void *data, int len)
 
 int main(int argc, char **argv)
 {
+    u64        final_exec_addr;
     u32        loadbase, dat_siz, mem_siz;
     char      *inimage, *outimage;
     int        infd, outfd;
@@ -234,15 +235,17 @@ int main(int argc, char **argv)
     Elf64_Ehdr in64_ehdr;
     Elf64_Phdr in64_phdr;
 
-    if ( argc != 4 )
+    if ( argc != 5 )
     {
-        fprintf(stderr, "Usage: mkelf32 <in-image> <out-image> <load-base>\n");
+        fprintf(stderr, "Usage: mkelf32 <in-image> <out-image> "
+                "<load-base> <final-exec-addr>\n");
         return 1;
     }
 
     inimage  = argv[1];
     outimage = argv[2];
     loadbase = strtoul(argv[3], NULL, 16);
+    final_exec_addr = strtoul(argv[4], NULL, 16);
 
     infd = open(inimage, O_RDONLY);
     if ( infd == -1 )
@@ -286,7 +289,10 @@ int main(int argc, char **argv)
 
         (void)lseek(infd, in32_phdr.p_offset, SEEK_SET);
         dat_siz = (u32)in32_phdr.p_filesz;
-        mem_siz = (u32)in32_phdr.p_memsz;
+
+        /* Do not use p_memsz: it does not include BSS alignment padding. */
+        /*mem_siz = (u32)in32_phdr.p_memsz;*/
+        mem_siz = (u32)(final_exec_addr - in32_phdr.p_vaddr);
         break;
 
     case ELFCLASS64:
@@ -314,7 +320,10 @@ int main(int argc, char **argv)
 
         (void)lseek(infd, in64_phdr.p_offset, SEEK_SET);
         dat_siz = (u32)in64_phdr.p_filesz;
-        mem_siz = (u32)in64_phdr.p_memsz;
+
+        /* Do not use p_memsz: it does not include BSS alignment padding. */
+        /*mem_siz = (u32)in64_phdr.p_memsz;*/
+        mem_siz = (u32)(final_exec_addr - in64_phdr.p_vaddr);
         break;
 
     default:

diff --git a/xen/arch/x86/boot/x86_32.S b/xen/arch/x86/boot/x86_32.S
index ca0c43555a540e8ac3862b63ed16c2194ac8792a..3294b7351a9a82106b4f57a2566025959e127f97 100644 (file)
--- a/xen/arch/x86/boot/x86_32.S
+++ b/xen/arch/x86/boot/x86_32.S
@@ -74,10 +74,6 @@ __start:
         cmp     $0x2BADB002,%eax
         jne     not_multiboot
 
-        /* Save the Multiboot info structure for later use. */
-       add     $__PAGE_OFFSET,%ebx
-        push    %ebx
-
         /* Initialize BSS (no nasty surprises!) */
         mov     $__bss_start-__PAGE_OFFSET,%edi
         mov     $_end-__PAGE_OFFSET,%ecx
@@ -85,6 +81,10 @@ __start:
         xor     %eax,%eax
         rep     stosb
 
+        /* Save the Multiboot info structure for later use. */
+        add     $__PAGE_OFFSET,%ebx
+        push    %ebx
+
 #ifdef CONFIG_X86_PAE
         /* Initialize low and high mappings of all memory with 2MB pages */
         mov     $idle_pg_table_l2-__PAGE_OFFSET,%edi
@@ -238,27 +238,28 @@ ENTRY(gdt_table)
         .fill 2*NR_CPUS,8,0          /* space for TSS and LDT per CPU    */
 
         .org 0x2000
-/* Maximum STACK_ORDER for x86/32 is 1. We must therefore ensure that the */
-/* CPU0 stack is aligned on an even page boundary!                        */
-ENTRY(cpu0_stack)
-        .org 0x2000 + STACK_SIZE
 
 #ifdef CONFIG_X86_PAE
-
 ENTRY(idle_pg_table)
 ENTRY(idle_pg_table_l3)
         .quad 0x100000 + 0x2000 + STACK_SIZE + 1*PAGE_SIZE + 0x01
         .quad 0x100000 + 0x2000 + STACK_SIZE + 2*PAGE_SIZE + 0x01
         .quad 0x100000 + 0x2000 + STACK_SIZE + 3*PAGE_SIZE + 0x01
         .quad 0x100000 + 0x2000 + STACK_SIZE + 4*PAGE_SIZE + 0x01
-        .org 0x2000 + STACK_SIZE + 1*PAGE_SIZE
+.section ".bss.page_aligned","w"
 ENTRY(idle_pg_table_l2)
-        .org 0x2000 + STACK_SIZE + 5*PAGE_SIZE
-
-#else /* CONFIG_X86_PAE */
-
+        .fill 4*PAGE_SIZE,1,0
+#else
+.section ".bss.page_aligned","w"
 ENTRY(idle_pg_table)
-ENTRY(idle_pg_table_l2) # Initial page directory is 4kB
-        .org 0x2000 + STACK_SIZE + PAGE_SIZE
+ENTRY(idle_pg_table_l2)
+        .fill 1*PAGE_SIZE,1,0
+#endif
 
-#endif /* CONFIG_X86_PAE */
+#if (STACK_ORDER == 0)
+.section ".bss.page_aligned","w"
+#else
+.section ".bss.twopage_aligned","w"
+#endif
+ENTRY(cpu0_stack)
+        .fill STACK_SIZE,1,0

diff --git a/xen/arch/x86/boot/x86_64.S b/xen/arch/x86/boot/x86_64.S
index fbe5311124fd0ca86ba4f167b1c45935b3b927f9..126850a0f8a8a698456895db4cff7eca82c828b6 100644 (file)
--- a/xen/arch/x86/boot/x86_64.S
+++ b/xen/arch/x86/boot/x86_64.S
@@ -249,13 +249,8 @@ ENTRY(idle_pg_table_4)
 ENTRY(idle_pg_table_l3)
         .quad idle_pg_table_l2 - __PAGE_OFFSET + 7
 
-        .org 0x4000
-/* Maximum STACK_ORDER for x86/64 is 2. We must therefore ensure that the */
-/* CPU0 stack is aligned on a 4-page boundary.                            */
-ENTRY(cpu0_stack)
-
 /* Initial PDE -- level-2 page table. Maps first 64MB physical memory. */
-        .org 0x4000 + STACK_SIZE
+        .org 0x4000
 ENTRY(idle_pg_table_l2)
         .macro identmap from=0, count=32
         .if \count-1
@@ -265,7 +260,15 @@ ENTRY(idle_pg_table_l2)
         .quad 0x00000000000001e3 + \from
         .endif
         .endm
-        identmap /* Too orangey for crows :-) */
+        identmap
 
-        .org 0x4000 + STACK_SIZE + PAGE_SIZE
+        .org 0x4000 + PAGE_SIZE
         .code64
+
+#if (STACK_ORDER == 0)
+.section ".bss.page_aligned","w"
+#else
+.section ".bss.twopage_aligned","w"
+#endif
+ENTRY(cpu0_stack)
+        .fill STACK_SIZE,1,0

diff --git a/xen/arch/x86/x86_32/xen.lds b/xen/arch/x86/x86_32/xen.lds
index fec62dbf2405dec9ecc1fe1f24214395e4d53ec6..f3c168f6620b99763438c76bbf1ff27076eacfb4 100644 (file)
--- a/xen/arch/x86/x86_32/xen.lds
+++ b/xen/arch/x86/x86_32/xen.lds
@@ -23,7 +23,6 @@ SECTIONS
   _etext = .;                  /* End of text section */
 
   .rodata : { *(.rodata) *(.rodata.*) } :text
-  .kstrtab : { *(.kstrtab) } :text
 
   . = ALIGN(32);               /* Exception table */
   __start___ex_table = .;
@@ -35,24 +34,11 @@ SECTIONS
   __pre_ex_table : { *(__pre_ex_table) } :text
   __stop___pre_ex_table = .;
 
-  __start___ksymtab = .;       /* Kernel symbol table */
-  __ksymtab : { *(__ksymtab) } :text
-  __stop___ksymtab = .;
-
-  __start___kallsyms = .;      /* All kernel symbols */
-  __kallsyms : { *(__kallsyms) } :text
-  __stop___kallsyms = .;
-
   .data : {                    /* Data */
        *(.data)
        CONSTRUCTORS
        } :text
 
-  _edata = .;                  /* End of data section */
-
-  . = ALIGN(8192);             /* init_task */
-  .data.init_task : { *(.data.init_task) } :text
-
   . = ALIGN(4096);             /* Init code and data */
   __init_begin = .;
   .text.init : { *(.text.init) } :text
@@ -64,10 +50,13 @@ SECTIONS
   __initcall_start = .;
   .initcall.init : { *(.initcall.init) } :text
   __initcall_end = .;
+  . = ALIGN(8192);
   __init_end = .;
 
   __bss_start = .;             /* BSS */
   .bss : {
+       *(.bss.twopage_aligned)
+       *(.bss.page_aligned)
        *(.bss)
        } :text
   _end = . ;

diff --git a/xen/arch/x86/x86_64/xen.lds b/xen/arch/x86/x86_64/xen.lds
index 30a2b0ca672221d76316b6f5bd2b01934ce42037..837d335f0dc52dbd2ff7ab518defcf3e68aeec2a 100644 (file)
--- a/xen/arch/x86/x86_64/xen.lds
+++ b/xen/arch/x86/x86_64/xen.lds
@@ -21,7 +21,6 @@ SECTIONS
   _etext = .;                  /* End of text section */
 
   .rodata : { *(.rodata) *(.rodata.*) } :text
-  .kstrtab : { *(.kstrtab) } :text
 
   . = ALIGN(32);               /* Exception table */
   __start___ex_table = .;
@@ -33,24 +32,11 @@ SECTIONS
   __pre_ex_table : { *(__pre_ex_table) } :text
   __stop___pre_ex_table = .;
 
-  __start___ksymtab = .;       /* Kernel symbol table */
-  __ksymtab : { *(__ksymtab) } :text
-  __stop___ksymtab = .;
-
-  __start___kallsyms = .;      /* All kernel symbols */
-  __kallsyms : { *(__kallsyms) } :text
-  __stop___kallsyms = .;
-
   .data : {                    /* Data */
        *(.data)
        CONSTRUCTORS
        } :text
 
-  _edata = .;                  /* End of data section */
-
-  . = ALIGN(8192);             /* init_task */
-  .data.init_task : { *(.data.init_task) } :text
-
   . = ALIGN(4096);             /* Init code and data */
   __init_begin = .;
   .text.init : { *(.text.init) } :text
@@ -62,10 +48,13 @@ SECTIONS
   __initcall_start = .;
   .initcall.init : { *(.initcall.init) } :text
   __initcall_end = .;
+  . = ALIGN(8192);
   __init_end = .;
 
   __bss_start = .;             /* BSS */
   .bss : {
+       *(.bss.twopage_aligned)
+       *(.bss.page_aligned)
        *(.bss)
        } :text
   _end = . ;